[PATCH v1 14/17] Fix handling of zero length ACLs for file creation

[rick.macklem@gmail.com]

From: Rick Macklem <rmacklem@uoguelph.ca>

Although it seems unlikely that a NFSv4.2 client would
specify deletion of an ACL for file object creation,
this patch applies the changes needed to support that
for a POSIX draft default ACL.

Signed-off-by: Rick Macklem <rmacklem@uoguelph.ca>
---
 fs/nfsd/vfs.c | 34 +++++++++++++++++++++++++++-------
 1 file changed, 27 insertions(+), 7 deletions(-)

diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c
index 146483bf8a65..c884c3f34afb 100644
--- a/fs/nfsd/vfs.c
+++ b/fs/nfsd/vfs.c
@@ -596,15 +596,35 @@ nfsd_setattr(struct svc_rqst *rqstp, struct svc_fh *fhp,
 	if (attr->na_seclabel && attr->na_seclabel->len)
 		attr->na_labelerr = security_inode_setsecctx(dentry,
 			attr->na_seclabel->data, attr->na_seclabel->len);
-	if (IS_ENABLED(CONFIG_FS_POSIX_ACL) && attr->na_pacl)
-		attr->na_paclerr = set_posix_acl(&nop_mnt_idmap,
-						dentry, ACL_TYPE_ACCESS,
-						attr->na_pacl);
-	if (IS_ENABLED(CONFIG_FS_POSIX_ACL) &&
-				attr->na_dpacl && S_ISDIR(inode->i_mode))
-		attr->na_dpaclerr = set_posix_acl(&nop_mnt_idmap,
+	if (IS_ENABLED(CONFIG_FS_POSIX_ACL) && attr->na_dpacl) {
+		if (!S_ISDIR(inode->i_mode))
+			attr->na_dpaclerr = -EINVAL;
+		else if (attr->na_dpacl->a_count > 0)
+			/* a_count == 0 means delete the ACL. */
+			attr->na_dpaclerr = set_posix_acl(&nop_mnt_idmap,
 						dentry, ACL_TYPE_DEFAULT,
 						attr->na_dpacl);
+		else
+			attr->na_dpaclerr = set_posix_acl(&nop_mnt_idmap,
+						dentry, ACL_TYPE_DEFAULT,
+						NULL);
+	}
+	if (IS_ENABLED(CONFIG_FS_POSIX_ACL) && attr->na_pacl) {
+		/*
+		 * For any file system that is not ACL_SCOPE_FILE_OBJECT,
+		 * a_count == 0 MUST reply nfserr_inval.
+		 * For a file system that is ACL_SCOPE_FILE_OBJECT,
+		 * a_count == 0 deletes the ACL.
+		 * XXX File systems that are ACL_SCOPE_FILE_OBJECT
+		 * are not yet supported.
+		 */
+		if (attr->na_pacl->a_count > 0)
+			attr->na_paclerr = set_posix_acl(&nop_mnt_idmap,
+							dentry, ACL_TYPE_ACCESS,
+							attr->na_pacl);
+		else
+			attr->na_paclerr = -EINVAL;
+	}
 out_fill_attrs:
 	/*
 	 * RFC 1813 Section 3.3.2 does not mandate that an NFS server
-- 
2.49.0